Corn or maize headers for harvesting machines comprise row units, each of which typically includes two gathering conveyors, two snapping rolls and a pair of associated stripper plates. The gathering conveyors extend along opposite sides of a stalkway, which is a fore and aft extending slot that is open on the front end. The snapping rolls also extend along the opposite sides of the stalkway, typically below the gathering conveyors, as do the stripper plates. The gathering conveyors typically comprise endless chains each of which encircles a drive sprocket adjacent to the aft end of the stalkway, and a front sprocket adjacent to the forward end. The chain includes sidewardly projecting gathering elements, which are also sometimes referred to as gatherers or lugs.
In operation, during forward movement of the harvester over a field, each row unit will be aligned with and driven along a row of corn. The corn stalks will be received through the front open end into the stalkway, and the snapping rolls rotate to pull the corn stalk downward and past the stripper plates. As the stalk is pulled downward, the ears of corn which are attached to the stalk are stripped from the stalk by the stripper plates. The stripped ears are then conveyed rearwardly to an auger of the header by the gathering conveyors. This operation is performed simultaneously by each of the row units.
The adjacent row units of a corn header are spaced apart at spacings corresponding to the spacings between the adjacent rows of corn, such that the stalk ways can be aligned with the individual rows. Because of the width of the apparatus on each side of the stalk way of a row unit, there is typically a minimum row spacing of twice this width, that is, a spacing that accommodates the apparatus on adjacent sides of two side by side row units. Mainly, this width is a function of the width of the gathering conveyor.
Numerous attempts to reduce the width of the gathering conveyors, have been made. Reference in this regard, Becker U.S. Pat. No. 5,826,415, entitled Corn Gathering and Conveying System, issued Oct. 27, 1998; and Johnson U.S. Pat. No. 5,878,560, entitled Narrow Row Corn Head With Tilted Gatherers, issued Mar. 9, 1999, both of which involve tilting of the gathering conveyors. Reference also, Gunn U.S. Pat. No. 5,878,561, entitled Row Crop Harvester, also issued Mar. 9, 1999; and Clarke U.S. Pat. No. 6,516,599, entitled Corn Harvester With Improved Ear Picking Mechanism, issued Feb. 11, 2003, both of which involve staggering adjacent conveyors vertically.
A shortcoming of tilting the gathering conveyors is that the adjacent conveyors must still be spaced apart sufficiently such that the gathering elements or lugs of the two conveyors do not contact. Stacking adjacent conveyors allows the gathering elements and even the conveyors themselves to overlap. However, this can be a shortcoming as it requires the adjacent conveyors to be mounted at different heights. And, as a result, the conveyors on the opposite sides of the respective stalk ways will be at different heights, which can cause conveying problems.
What is sought therefore, is a gathering conveyor construction that can be incorporated into a row unit, which allows further reducing the spacing between adjacent row units, but which overcomes at least one of the shortcomings and limitations of the known constructions.